Mold for bonded seals



Jan. 20, 1970 s. A. SMITH ETAL MOLD FOR BONDED SEALS 2 Sheets-Sheet 1Original Filed Sept. 14, 1961 I .TLZKEFQZQQEH STANLEY A. SMTH WARREN W.RASMUSSEM Jan; 20, 1970 s. A. SMITH ETAL MOLD FOR BONDED SEALS 2Sheets-Sheet 2 Original Filed Sept, 14. 1961 STANLEY A. SMlTH WARREN W.RASMUSSEN United States Patent Office 3,490,099 Patented Jan. 20, 19703,490,099 MOLD FOR BONDED SEALS Stanley A. Smith, Elgin, and Warren W.Rasmussen,

Elmhurst, Ill., assignors to Chicago Rawhide Manufacturing Company,Chicago, 111., a corporation of Illinois Continuation of applicationSer. No. 471,488, May 26, 1965, which is a division of application Ser.No. 138,142, Sept. 14, 1961. This application Sept. 16, 1966, Ser. No.586,911

Int. Cl. B29d 3/00 U.S. Cl. 1836 4 Claims ABSTRACT OF THE DISCLOSURE Amold for flash-free molding of bonded seals in which a U-shaped cavityis provided to receive a U-shaped portion of a seal stamping, and inwhich an upper land of the mold moves into position to engage oneportion of the U-shaped stamping along a line at the top thereof, whileanother portion of the mold engages the U-shaped portion along an outersurface thereof. A separate abutment plate is provided to support thestamping in position within the mold in a position spaced apart from theportions thereof which form the flash barriers. The method includes thesteps of engaging the stamping along one axially extending surface ofthe U, and along a line of contact which is concentric therewith nearthe top surface of the other leg of the U, as the mold is closed to fillthe stamping with the rubbery material.

This is a continuation of our application Ser. No. 471,488, filed May26, 1965, now abandoned, which was a division of application Ser. No.138,142, filed Sept. 14, 1961, now Patent No. 3,241,845.

The invention relates to a new and improved type of mold for fabricatinga bonded oil seal. More specifically, the invention deals with a moldcapable of forming a W- type stamping bonded seal in a unique manner toprevent flash formation along surface portions of the stamping adjacentsealing member bonding areas.

Various forms of W-type stampings used in forming an oil seal having asealing member clamped by the stamping are well known, such as shown inthe Winter Patents No. 2,089,461 and 2,089,462. The basic W-typestamping was originally designed for the provision of an annular,generally U-shaped sealing member attaching portion into which an edgeof a sealing member or lip is inserted and then clamped by the bendingof a free leg segment of the mounting portion toward the opposite legsegment thereof. To this extent the W-type stamping has been usedsuccessfully particularly in the clamped mounting of a leather seal.

With the widespread use of molded rubber or other homogeneous resinousmaterial in the forming of sealing members, various types of molds havebeen used which are adapted to receive therein a stamping and, duringshaping of the rubber to form the sealing member, provide forsimultaneous bonding of the sealing member to the stamping. Problemshave arisen with regard to obtaining an adequate bond capable ofestablishing and maintaining attachment between the sealing member andstamping during subsequent extended use of the seal. Several differentoil seal designs have been utilized in an eifort to improve the bondedcharacteristics of the sealing member and stamping. By way of example,widespread use has been made of a design wherein the stamping portion towhich the sealing member is bonded is provided with spaced grooves oropenings which are filled by the resinous material with this materialcompletely overlying the stamping portion to an extent that the latteris substantially embedded in the sealing member. With these variousdesigns, the problem of flash control or elimination has always beenpresent. As is well recognized, it is desirable to eliminate flashestablished by a thin non-functional film of rubber spread over thestamping area immediately adjacent the sealing member bonding orattachment area. The oil seal industry has resorted to finishing orcleaning procedures to remove the flash following removal of thecompleted seal from the mold. Such procedures add substantially to theover-all cost of fabrication of the seal.

It is an object of this invention to provide a new and improved moldspecially adapted for use in the forming of a bonded W-type oil seal andincluding means co-operating with a W-type stamping to establish animproved bonded interconnection between a resinous sealing memberundergoing shaping and the sealing member mounting portion of thestamping, the mold further co-operating with the stamping to prevent theformation of flash thereon.

Other objects not specifically set forth will become apparent from thefollowing detailed description of the invention made in conjunction withthe accompanying drawings wherein:

FIG. 1 is a fragmentary section of one form of improved oil seal;

FIG. 2 is a cross sectional half view of a special mold of the inventioncapable of forming the seal of FIG. 1;

FIG. 3 is a cross sectional half view of the stamping used in formingthe seal of FIG. 1, the stamping being illustrated prior to insertion inthe mold of FIG. 2.

FIG. 4 is a view similar to FIG. 1 illustrating a modified form of seal;and

FIG. 5 is a view similar to FIG. 2 illustrating the mold used in formingthe seal of FIG. 4.

In general, the oil seal produced from the invention includes the use ofa casing of generally W-shape having an annular U-shaped sealing membermounting portion in which the base portion of a flexible resinoussealing member is received in bonded relation with the inner surfaces ofthe mounting portion, the base portion projecting from the mountingportion and having formed integral therewith a flexible diaphragmportion and sealing lip, the diaphragm portion overlying a radial edgesurface of the mounting portion and being bonded thereto in backed-uprelation. The seal 10 of FIG. 1 includes these features. This seal isformed from a generally W- shaped stamping which includes an axiallyextending seal mounting portion 11 integrally joined with a radiallyinwardly inclined segment 12 as viewed, this segment being integrallyjoined with the outermost axially directed leg segment 13 of a radiallyinwardly oflset sealing member mounting portion of generally annularU-shape, which mounting portion includes in addition to the leg segment13, a base segment 14 and an opposite free leg segment 15. The legsegments 13 and 15 are in parallel relation with the base segment 14radially interconnecting the same.

The seal 10 includes a resinous flexible sealing member 16 formed fromany suitable material such as rubber or synthetic rubber-like material.This sealing member includes a base portion 17 of block-likeconfiguration which completely fills the interior of the U-shapedmounting portion of the stamping and is continuously bonded to the innersurfaces of the leg segments 13, 14 and 15 thereof. The base portion 17projects to a limited extent from the mounting portion of the stampingand is integrally joined with a flexible intermediate diaphragm portion18 which in turn is integrally joined with a sealing leg portion 19 ofknown configuration including a spring mounting groove 20. The diaphragmportion 18 along the inner surface thereof fully overlies the free edge21 of the leg segment of the mounting portion of the stamping and isbonded thereto throughout the extent of covering relation. In thisrespect the diaphragm portion 18 is, in effect, offset radially inwardlyand is in attachment with the inner corner portion of the base 17 toplace the same in position to be substantially backedup by the free edgeof the leg segment 15 of the stamping mounting portion.

In the finished condition of the seal 10, the parallel leg segments 13and 15 are in completely relaxed condition maintaining their parallelrelation with the sealing member base portion 17 completely filling thearea therebetween. This base portion is, for all practical purposes,fully confined in the generally -U-shaped mounting portion of thestamping and with this arrangement a very substantial bonding area isprovided, this area being fully protected under all operatingconditions. Additionally, the intermediate diaphragm portion 18 of thesealing member 16 is reinforced or backed-up in protected relation bythe free edge 21 of the leg segment 15. Diaphragm portions are generallythin in shape to provide the requisite flexibility to the lip portionfor movement relative to the fixed casing of a seal and such diaphragmportions are often subject to damage or excessive wear. With thearrangement described the intended functioning of the diaphragm portion18 is retained while the same is substantially protected against damagewith the additional feature of this diaphragm portion actually providingan additional area of bonded attachment along the free edge 21 whichmaterially adds to the over-all resistance to separation of the sealingmember 16 from the stamping. The complete bond area providing forattachment of the sealing member 16 to the stamping is fully enclosed orcovered and the general arrangement and location of this area in themanner described protects the same from the application of anysubstantial stress resulting from forces applied to the sealing lipportion 19. The design described is uncomplicated and provides completeprotection to the bond area establishing connection between the sealingmember and the stamping. Sealing member shaping and bonding to thestamping may be readily accomplished as will be described.

FIG. 2 illustrates a mold 22 used in forming the seal 10. This moldincludes co-operating top and bottom plate structures which receivetherebetween the stamping and a biscuit of resinous stock material, andwhich upon closing, co-operatively shape the stock material to form thesealing member and while doing so, cause the stock material to flow intofilling bonded relation with the mounting portion of the stamping. Thebottom plate structure includes a center bottom die member 23 having aprojecting center pin 24 mounted thereon and received in a centralopening 25 in a top die member 26 forming a part of the top platestructure. The bottom die member 23 has received thereabout a radiallydirected stamping abutment plate 27 of annular configuration which ismounted on an annular spacer plate 28. A bottom cover plate 29 extendsacross the spacer plate 28 and bottom die member 23 and is suitablyattached thereto by fasteners 30. The top plate structure includes thetop die member 26 and an annular guide plate 31 received thereabout andhaving attached thereto a top cover plate 32 by means of fasteners 33. Aplurality of circumferentially spaced guide pins 34 extend upwardly fromthe bottom plate structure and are received in aligned apertures in theplates 31 and 32.

The bottom die member 23 is formed with an annular, upwardly openinggroove 35 in which is snugly received the U-shaped mounting portion ofthe stamping. The inner wall portion of the groove 35 extends upwardlytherefrom and is shaped along the upper extension, generally designatedby the numeral 36, to form the sealing member 16. This area 36 of thebottom die member may take any desired shape depending upon the intendedfinal C011- figuration of the sealing member. However, the upwardextension of the inner side wall portion of the groove 35 must be suchto define the offset diaphragm portion bonded to the free edge of theleg segment 15 previously described.

The opposite or outer side wall portion of the groove 35 is defined byan annular upstanding ridge 37 the outer surface of which is inclined togenerally parallel the intermediate segment 12 of the stamping in spacedrelation therewith. The height of the ridge 37 is such that the innervertical surface thereof adequately supports and engages the leg segment13 but a clearance is established between the top edge of the ridge 37and the stamping to prevent stamping bottoming thereon. The arcuate areaof juncture of the axially directed segment 11 and the intermediatesegment 12 of the stamping is placed in resting engagement on the topsurface of the abutment plate 27. This top surface is in radialalignment with the bottom surface of the groove 35.

The top die member 26 is formed with an annular depending rim-likeportion 38 the inner surface of which is shaped along the general areadesignated by the numeral 39 to conform to the final shaping of thesealing member 16 including the spring mounting groove 20 thereof. Theouter surface of the depending portion 38 is generally vertical forsubstantial clearance inwardly of the axially directed segment 11 of thestamping. The bottom edge of the depending portion 38 is formed with adownwardly projecting shoulder portion 40 located adjacent the innersurface area 39. The outermost edge 41 of the shoulder portion 40 is ofgenerally sharp, right angle configuration to define a land whichengages the stamping just outwardly of the U-shaped mounting portion andadjacent the juncture of the leg segments 12 and 13. The outermostsurface portion of the bottom of the depending portion 38 is recessedsufiiciently to maintain clearance with the stamping when the mold iscompletely closed as illustrated in FIG. 2.

The operation of the mold 22 involves the placing of the stamping inoperative position on the bottom die member 23 when the mold is open.Suitable stock material is placed on the annular surface portion 42 ofthe bottom die member 23 and the top plate structure is put in place andpressure is applied to close the mold assembly. Movement of the top andbottom plate structures toward one another result in the flow of stockmaterial into the area defined between the surface portions 36 and 39and downwardly toward the mounting portion of the stamping. The land 41engages the stamping and this engagement may be used to force themounting portion of the stamping down into the groove 35 or the stampnigmay be pressed into the groove 35 prior to mold closing. The mold partsare dimensioned to provide for flow of stock material into the mountingportion of the stamping upon engagement of the land 41 with the stampingand bottoming of the stamping in the groove 35 and against the abutmentplate 27. Complete closing of the mold results in adequate embedding ofthe land 41 in the material of the stamping to prevent the flow of stockmaterial outwardly of the mounting portion along the adjacent surface ofthe stamping. In this uncomplicated matter the formation of flash beyondthe base portion 17 of the sealing member is eliminated.

To eliminate flash formation along the outer surfaces of the legsegments 13, 14 and 15 of the mounting portion of the stamping, thegroove 35 is dimensioned to snugly and tightly receive the mountingportion therein. The opposite side surfaces of the groove 35 engage theouter surfaces of the leg segments 13 and 15 in tight co-extensiverelation thus preventing fiow of stock material therebetween. The amountof surface area contact is substantial by reason of the design of thegroove and the shape of the stamping and this factor materially aids inthe control of stock material flow. As is conventional, adequate heat isapplied during the molding operation to provide for stock material flow,curing and bonding thereof.

If desired, the stamping may be in the form illustrated in FIG. 3 priorto insertion in the mold. In this form the free leg segement 15 of themounting portion of the stamping is slightly inclined inwardly away fromthe opposite leg segement 13. Upon insertion of the mounting portion inthe groove 35 of the mold, the leg segment 15 is bent outwardly intoparallel relation with the leg segment 13 as indicated in broken linesin FIG. 3. The bending is of a permanent nature to fix the leg segment15 in this final position and during bending thereof, intimate contactis maintained and established between the surface of the leg segment inengagement with the side surface of the groove 35. In this manner anadded precaution may be relied upon to prevent the formation of flashalong any outer surface portion of the mounting portion of the stamping.

Certain modifications of seal configuration can be made within the scopeof the invention, one such modification being illustrated in FIG. 4. Theseal 43 of FIG. 4 is basically of the same design as the seal describedabove and similar parts thereof are identified by the same referencenumerals. The main modification occurring in the seal 43 involves theprovision of a reversely inclined secondary sealing lip 44 formedintegrally with the diaphragm portion 18 of the sealing member 16 andlocated outwardly of the sealing member mounting portion of the stampingand directed rearwardly relative thereto. The secondary sealing lip 44can function as a wiper member or dirt excluder and its efiiciency inperforming this function is enhanced by the proximity of thestrengthening or rigidifying leg segment with its free edge 21 bonded tothe diaphragm portion 18 immediately outwardly of the sealing lip 44. Abase portion 45 of the sealing lip 44 overextends the adjacent edge ofthe leg segment 15 in bonded relation therewith.

FIG. 5 illustrates a suitable mold 46 capable of forming the seal 43.This mold generally comprises a top plate 47 and a bottom platestructure including a center core member 48, an annular die plate 49, anannular stamping abutment plate 50 and a lock plate 51 attached to thecenter core 48 by suitable fasteners 52. The center core has mountedtherein a center pin 53 which is received in a center bore 54 of the topplate. The center core 48 includes an annular, radially projecting dieportion 55 provided with an outer sealing member shaping surface 56which functions to shape the lip portions 19 and 44. A top surfaceportion 57 receives the resinous stock material thereon prior to closingof the mold. The die plate 39 is formed with an annular upwardly openinggroove 58 which is identical in function to the groove 35 previouslydescribed. The groove 58 is formed from an inner upstanding rim 59 theouter surface of which is vertical to define a groove side wall and theinner surface of which is inclined and joined with the outer surfacethrough an arcuate top surface. The rim 59 functions cooperatively withthe sealing member shaping surface 56 and leg segment 15 of the stampingto form the secondary sealing lip portion 44 previously described. Theouter vertical wall surface of the groove 58 is defined by an annularupstanding rib 60 which is of a shape similar to the rib 37 previouslydescribed and functions in the same manner. The top plate 47 is providedwith an annular depending portion 61 the inner surface area 62 of whichco-operatively functions with the surface area 56 to shape the sealingmember. The bottom surface of the portion 61 is formed with a dependingshoulder portion 63 the outermost edge 64 of which constitutes arelatively sharp land which becomes embedded in the stamping to preventthe formation of flash. The stamping abutment plate 50 aids insupporting the stamping in the mold and the mold operates in the samemanner as previously described.

From a comparison of the molds 22 and 46, it will be apparent thatvariations in sealing member shape may be resorted to while retainingthe advantages of establishing an improved bond and flashless parts. Theprovision of a substantial bonding area, protection of the bonding areaagainst operational stresses, and mold design simplicity leads to newand improved results. It will be noted that the basic design concepts ofthe top plates of each of the molds described are sufliciently similarto permit interchangeability in the fabrication of seals having sealingmembers of varying configurations.

Obviously certain modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposed asare indicated in the appended claims.

We claim:

1. A mold for use in the fabrication of an oil seal which includes acasing of generally W-shape having an axially directed outermost segmentjoined by a radially inclined segment to a radially inwardly offset,generally U-shaped sealing member mounting portion, said mold comprisingco-operating top and bottom plates, said bottom plate being formed withan annular upwardly opening groove in which the U-shaped sealing membermounting portion of said casing is adapted to be received in radiallyconfined relation, a side wall portion of said groove including anupwardly extending portion shaped to form a sealing member forattachment to said casing, separate, circularly extending abutment meanspositioned radially relative to said bottom plate for resting engagementof said casing thereon adjacent said axially directed outermost segmentthereof, said top plate including an annular depending sealing membershaping portion for co-operation with the upper extension of said sidewall portion of said groove, the bottom edge portion of said dependingsealing member shaping portion being formed with an annular land forengagement with said casing immediately adjacent the juncture of saidU-shaped sealing member mounting portion with said radially inclinedsegment to close off said mounting portion and prevent the flow ofsealing member forming material outwardly of said U-shaped mountingportion along the radially outer surfaces of said portion during shapingof said sealing member and bonding thereof to said casing.

2. A mold for use in the fabrication of an oil seal which includes acasing of generally W-shape having an axially directed outermost segmentjoined by a radially inclined segment to a radially inwardly offset,generally shaped sealing member mounting portion, said mold comprisingco operating top and bottom plates, said bottom plate being formed withan annular upwardly opening groove in which the U-shaped sealing memberrnountlng portion of said casing is adapted to be received in radiallyconfined relation, a side wall portion of said groove including anupwardly extending portion shaped to form a sealing member forattachment to said casing, separate, circularly extending abutment meanspositioned radially relative to said bottom plate for resting engagementof said casing thereon adjacent said axially directed segment thereof,said top plate including an annular depending sealing member shapingportion for co-operation with the upper extension of said side wallportion of said groove, the bottom edge portion of said dependingsealing member shaping portion being formed with an annular land forengagement with said casing immediately adjacent the juncture of saidU-shaped sea-ling member mounting portion with said radially inclinedsegment to close off said mounting portion and prevent the flow ofsealing member forming material outwardly of said U-shaped mountingportion along the radially outer surfaces of said portion during shapingof said sealing member and bonding thereof to said casing, said groovebeing dimensioned to tightly receive the sealing member mounting portionof said casing therein in upwardly opening relation to prevent the flowof sealing member forming material into said groove.

3. A mold for use in the fabrication of an oil seal which includes acasing of generally W-shape having an axially directed outermost segmentjoined by a radially inclined segment to a radially inwardly oifset,generally U-shaped sealing member mounting portion, said mold comprisingco-operating top and bottom plates, said bottom plate being formed withan annular upwardly opening groove in which the U-shaped sealing membermounting portion of said casing is adapted to be received in radiallyconfined relation, an annular ridge defining one side wall portion ofsaid groove and arranged for reception between said U-shaped sealingmember mounting portion and said radially inclined segment of saidcasing, the opposite side wall portion of said grooveincluding anupwardly extending portion shaped to form a sealing member forattachment to said casing, separate, circularly extending abutment meanspositioned radially relative to said bottom plate for resting engagementof said casing thereon adjacent said axially directed segment thereof,said top plate including an annular depending sealing member shapingportion for co-operation with the upper extension of said opposite sidewall portion of said groove, the bottom edge portion of said dependingsealing member shaping portion being formed with an annular land forengagement with said casing immediately adjacent the juncture of saidU-shaped sealing member mounting portion with said radially inclinedsegment to close off said mounting portion and prevent the flow ofsealing member forming material outwardly of said U-shaped mountingportion along the radially outer surfaces of said portion during shapingof said sealing member and bonding thereof to said casing.

4. A mold for use in the fabrication of an oil seal which includes acasing of generally W-shape having an axially directed outermost segmentjoined by a radially inclined segment to a radially inwardly oil'set,generally U-shaped sealing member mounting portion, said mold comprisingco-operating top and bottom plates, said bottom plate being formed withan annular upwardly opening groove in which the U-shaped sealing membermounting portion of said casing is adapted to be received in radiallyconfined relation, an annular ridge defining one side wall portion ofsaid groove and arranged for reception between the sealing membermounting portion and said radially inclined segment of said casing, theopposite side wall portion of said groove including an upwardly extending portion shaped to form a sealing member for attachment to saidcasing, separate, circularly extending abutment means positionedradially relative to said bottom plate for resting engagement of saidcasing thereon adjacent said axially directed segment thereof, said topplate including an annular depending sealing member shaping portion forco-operation with the upper extension of said opposite side wall portionof said groove, the bottom edge portion of said depending sealing membershaping portion being formed with an annular land for engagement withsaid casing immediately adjacent the juncture of said U-shaped sealingmember mounting portion with said radially inclined segment to close offsaid mounting portion and prevent the flow of sealing member formingmaterial outwardly of said U-shaped mounting portion along the radiallyouter surfaces of said portion during shaping of said sealing member andbonding thereof to said casing, said groove being dimensioned to tightlyreceive the sealing member mounting portion of said casing therein inupwardly opening relation to prevent the flow of sealing member formingmaterial into said groove.

References Cited UNITED STATES PATENTS 2,089,461 8/1937 Winter 277-2,479,350 8/1949 Haggart 1836 X 2,982,999 5/1961 Stewart 18-36 X3,004,298 l0/ 1961 Haynie l836 X 3,090,996 5/1963 Reichenbach 264266 X2,949,635 8/1960 Chiero 18-36 3,004,297 10/ 1961 Stover 264268 X ROBERTF. WHITE, Primary Examiner N. RUSHEFSKY, Assistant Examiner US. Cl. X.R.264-268

